A transmit diversity technology can effectively reduce channel fading and improve reliability of a communications system. Alamouti encoding is a classic space time coding scheme based on transmit diversity, and construction is easy and decoding is simple. However, filter bank-based multi carrier (Filter Bank-based Multi Carrier, FBMC) has an imaginary part interference problem, and can hardly be combined with Alamouti encoding.
A block Alamouti scheme is proposed in the prior art. In this scheme, space time block code (Space Time Block Code, STBC) is combined with the FBMC, and a guard interval needs to be added in a time domain to eliminate impact of imaginary part interference. Because the FBMC uses a prototype filter of a relatively long impulse response, a symbol transmitted in the time domain suffers imaginary part interference from multiple symbols. Therefore, the guard interval added in the time domain is quite large, which causes relatively low system efficiency.
A difficulty of combining the FBMC with Alamouti encoding lies in the impact of imaginary part interference. How to reduce the impact of imaginary part interference without using a guard interval is a problem that the present invention intends to resolve.